The present invention relates to an anti-rolling gyroscopic stabilizer for boats, comprising a stationary frame having, connected thereto, a frame rotatable about a first axis and supporting a flywheel rotatable about a second axis perpendicular to the first axis.
An anti-rolling gyroscopic stabilizer of the aforementioned type makes use of the gyroscopic effect in order to dampen the rolling oscillation of the boat on which the stabilizer is mounted.
The gyroscopic effect occurs when a mass, caused to rotate about a generic first axis, owing to the action of an external force is subject to a rotation about a second axis perpendicular to the first axis, thereby generating a precession movement of the first axis in a direction perpendicular to the plane defined by the first and second axes.
The gyroscopic stabilizer performs the aforementioned damping action, opposing rolling movement with a reaction which is in counter-phase with respect thereto. For example, if it is assumed that the rolling movement has a sinusoidal characteristic (usually in phase with the acting force, or with the wave, in the case of a boat), the ideal reaction of the stabilizer would have a characteristic, which is also sinusoidal, offset or out of phase by 180° with respect to the acting force.
Furthermore there exists the problem of preventing the action, exerted by the gyroscopic effect on the flywheel support elements, from being concentrated within time transients which are too short, so as not to stress these support elements excessively. The prior art envisages, as a solution to the aforementioned problem, the use of devices for damping the precession velocity, which act on at least one of the pivots connecting together the fixed frame, integral with the boat, and the frame supporting the flywheel. Generally, the flywheel frame is suspended in an oscillating manner with respect to the fixed frame.
Oscillation of the flywheel frame must be limited, not only in terms of velocity, but also in terms of angular amplitude, such that it does not adversely affect the gyroscopic effect which helps stabilize the rolling movement. In fact, with an increase in the oscillation amplitude, the rolling opposition function of the gyroscopic effect will tend to diminish all the more, while increasing yawing of the boat. Therefore, it can be deduced that maximum stabilization of rolling by the gyroscopic effect is obtained with amplitudes of the precession movement which are close to zero, with respect to the direction which the axis of rotation of the flywheel would assume, relative to a fixed reference point integral with the external frame, assuming a condition of the stationary frame/oscillating frame/flywheel being undisturbed by external forces.
On the other hand, damping elements intended to limit the amplitude and velocity of oscillation of the frame do not help restore the optimum configuration. This is because the damping elements prevent (or at least do not facilitate) the return of the axis of rotation of the flywheel into the position which it would have assumed, relative to a fixed reference point integral with the external frame, in the case of an undisturbed condition of the stationary frame/oscillating frame/flywheel assembly.
This functional deficiency results in two main problems which concern: the efficiency of the device, since the capacity of influencing stabilization of the rolling movement is limited, owing to the fact that there is no active solution for restoring the optimum configuration of the relative positions of stationary frame, oscillating frame and flywheel; the reactivity of the device, since it tends to remain in the disturbed configuration as a result of inertia. This prevents, for example, any counter-turning manoeuvre where a first turning movement to one side of the hull is followed rapidly by a second turning movement to the opposite side.